The present invention relates to spark plugs used to ignite fuel in internal combustion spark-ignited engines. Present day spark plug technology dates back to the early 1950's with no dramatic changes in design except for materials and configuration of the spark gap electrodes. These relatively new electrode materials such as platinum and iridium have been incorporated into the design to mitigate the operational erosion common to all spark plugs electrodes in an attempt to extend the useful life. While these materials will reduce electrode erosion for typical low power discharge (less than 1 ampere peak discharge current) spark plugs and perform to requirements for 109 cycles, they will not withstand the high coulomb transfer of high power discharge (greater than 1 ampere peak discharge current). Additionally, there have been many attempts at creating higher capacitance in the spark plug or attaching a capacitor in parallel to existing spark plugs. While this will increase the discharge power of the spark, the designs are inefficient, complex and none deal with the accelerated erosion associated with high power discharge.
U.S. Pat. Nos. 3,683,232, 1,148,106 and 4,751,430 discuss employing a capacitor or condenser to increase spark power. There is no disclosure as to the electrical size of the capacitor, which would determine the power of the discharge. Additionally, if the capacitor is of large enough capacitance, the voltage drop between the ignition transformer output and the spark gap could prevent gap ionization and spark creation.
U.S. Pat. No. 4,549,114 claims to increase the energy of the main spark gap by incorporating into the body of the spark plug an auxiliary gap. The use of two spark gaps in a singular spark plug to ignite fuel in any internal combustion spark ignited engine that utilizes electronic processing to control fuel delivery and spark timing could prove fatal to the operation of the engine as the EMI/RFI emitted by the two spark gaps could cause the central processing unit to malfunction.
In U.S. Pat. No. 5,272,415, a capacitor is disclosed attached to a non-resistor spark plug. Capacitance is not disclosed and nowhere is there any mention of the electromagnetic and radio frequency interference created by the non-resistor spark plug, which if not properly shielded against EMI/RFI emissions, could cause the central processing unit to shut down or even cause permanent damage.
U.S. Pat. No. 5,514,314 discloses an increase in size of the spark by implementing a magnetic field in the area of the positive and negative electrodes of the spark plug. The invention also claims to create monolithic electrodes, integrated coils and capacitors but does not disclose the resistivity values of the monolithic conductive paths creating the various electrical components. Electrical components conductive paths are designed for resistivity values of 1.5-1.9 ohms/meter ensuring proper function. Any degradation of the paths by migration of the ceramic material inherent in the cermet ink reduces the efficacy and operation of the electrical device. In addition, there is also no mention of the voltage hold-off of the insulating medium separating oppositely charged conductive paths of the monolithic components. If standard ceramic material such as Alumina 86% is used for the spark plug insulating body, the dielectric strength, or voltage hold off is 200 volts/mil. The standard operating voltage spread for spark plugs in internal combustion spark ignited engines is from 5 Kv to 20 Kv with peaks of 40 Kv seen in late model automotive ignitions, which might not insulate the monolithic electrodes, integrated coils and capacitors against this level of voltage.
U.S. Pat. Nos. 5,866,972, 6,533,629 and 6,533,629 speak to the application, by various methods and means, electrodes and or electrode tips consisting of platinum, iridium or other noble metals to resist the wear associated with spark plug operation. These applications are likely not sufficient to resist the electrode wear associated with high power discharge. As the electrode wears, the voltage required to ionize the spark gap and create a spark increases. The ignition transformer or coil is limited in the amount of voltage delivered to the spark plug. The increase in spark gap due to accelerated erosion and wear could be more than the voltage available from the transformer, which could result in misfire and catalytic converter damage.
U.S. Pat. No. 6,771,009 discloses a method of preventing flashover of the spark and does not resolve issues related to electrode wear or increasing spark discharge power.
U.S. Pat. No. 6,798,125 speaks to the use of a higher heat resistance Ni-alloy as the base electrode material to which a noble metal is attached by welding. The primary claim is the Ni-based base electrode material, which ensures the integrity of the weld. The combination is said to reduce electrode erosion but does not claim to either reduce erosion in a high-power discharge condition or improve spark power.
U.S. Pat. No. 6,819,030 for a spark plug claims to reduce ground electrode temperatures but does not claim to reduce electrode erosion or improve spark power.